This invention relates to apparatus and methods for applying adhesive to sheets of a set and assembling the sets into a bound booklet.
U.S. Pat. No. 3,404,880 issued on Oct. 8, 1968 in the names of H. R. Porter, Jr. et al for a GLUING ATTACHMENT FOR A COLLATING MACHINE. The apparatus disclosed in the Porter Jr. et al patent comprises a collator which holds stacks of sheets adjacent to a conveyor, and sheet transfer means which transfers individual sheets onto the conveyor. As each sheet is lifted from the stack and placed on the conveyor a small spot of glue is applied to the sheet so that when the sheets are assembled into a booklet the glue is effective to hold the sheets together. U.S. Pat. No. 3,114,543 issued to L. H. Bishop et al on Dec. 17, 1963 and also discloses a collator/binder for producing forms wherein rows of adhesive are applied to all but one sheet of a form and then the sheets are pressed together.
Automated sheet binding apparatus and methods for producing booklets on an on-line basis is disclosed in the beforementioned U.S. patent application Ser No. 380,966 entitled BINDING APPARATUS AND METHOD. As disclosed in such application, sets of sheets are fed seriatim from a copier/duplicator or the like directly into the binding apparatus. The individual sheets of a set are quickly advanced through the binder where adhesive is applied to all but one sheet of the set, the sheets are assembled into sets in an assembly tray with the adhesive between adjacent sheets, the sheets are pressed together in the area of the adhesive, and a completed booklet is discharged from the assembly tray to a tote tray. Some finishing operations in the assembly tray occur after the last sheet of a set is received in the assembly tray. For example, a pressure bar assembly compresses the sheets of the set in the area directly over the adhesive to assist in formation of the booklet. After the pressure bar assembly has been retracted, the assembly tray swings to an open position, and the completed booklet drops from the tray into a tote tray. When the binding apparatus works in connection with copier/duplicators having a relatively high output rate (e.g., 4,000 to 8,000 copies per hour) it is important that the steps required for completing one booklet be carried out prior to the time the first sheet of the next set of sheets reaches the assembly tray. Time for completing the finishing steps and removing the booklet from the tray can be obtained by controlling the copier/duplicator so that there is a time delay between delivery of sets of sheets to the binder. However, it clearly is more desireable to provide binding apparatus which can receive sets of sheets as fast as they are produced by the copier/duplicator and without interfering with the normal machine cycle of the copier/duplicator.
A similar problem occurs in a finisher for producing stapled booklets from sets of copies received from a copier/duplicator. Such a finisher is disclosed in commonly assigned U.S. Pat. No. 4,134,672 which issued on Jan. 16, 1979 in the names of Burlew et al and entitled COPIER FINISHER FOR AN ELECTROPHOTOGRAPHIC REPRODUCING DEVICE. The stapler finisher disclosed in such patent feeds a set of sheets into an assembly tray, jogs the sheets into alignment and then applies one or more staples to the set to form a booklet. Then the completed booklet is removed from the assembly tray and delivered to a tote tray where a stack of such booklets can be accumulated. The steps of jogging, stapling and removing of a finished booklet from the assembly tray does require a finite period of time during which time sheets of another set can be delivered to the finisher from the copier/duplicator. Therefor. the finisher provides a momentary interruption in the flow of sheets to the assembly tray by braking a pair of nip rollers located along the path traveled by the copy sheets between the copier/duplicator and the assembly tray. More specifically, the first two copy sheets of a set travelling along the sheet path are held up at the nip rollers. This provides sufficient time for the preceeding set of copy sheets to be jogged, stapled, and removed from the assembly tray before sheets of the next set are fed to the tray. While merely braking a pair of nip rollers along the sheet path is sufficient to provide the needed time in a stapler finisher of the type disclosed in such patent, this solution is not entirely satisfactory in an adhesive binder because the accumulation of two sheets along the common sheet path leading to the assembly tray will cause wiping of adhesive along the interface between the two sheets as the second sheet moves along the first sheet before the second sheet reaches the nip. Such wiping of the adhesive can remove a sufficient portion of the adhesive from the desired area of the sheet to cause an unsatisfactory bond to be produced between the sheets when they are finally delivered to the assembly tray for formation into a booklet.